The present invention relates to machines for winding electrical wire coils and more particularly to coil winding machines for winding saddle-shaped coils.
At the present time it is known that wires carrying electrical current may be wound into coils of many shapes and sizes. It has been found, after years of intensive theoretical and practical studies by leading electronic companies, that various configurations of saddle-shaped coils provide the desired electromagnetic fields in various applications. Generally the size, wire configuration and external shape of the saddle-shaped coil is proprietary, or of special design, and associated with a specific utilization, for example, as the vertical deflection coil in a 19-inch shadow mask type of color television picture tube. Other uses for saddle-shaped coils include vertical and horizontal wide-angle deflection yokes in which the coils are sometimes called "saddle yokes", beam deflection coils in CRT tubes for computer display terminals and other uses.
Many of these saddle-shaped coils present difficult requirements to meet in production. Their shape is often highly complex with the same wire in a single turn lying flat in two different planes, being vertical and turning in three of four directions. It is desired, in order to obtain an accurate electromagnetic field, that each coil, insofar as possible, have its wires spaced according to a predetermined pattern. The wires have a conductive core, generally of copper or a copper alloy, covered by an insulative varnish, generally of a plastic resin. The insulative varnish is selected so that it softens or melts under heat to adhere the wires to each other.
One type of machine presently used to wind such saddle-shaped coils mounts a mandrel, i.e., a form around which the coil is wound, and rotates the mandrel in a lath-like machine. The rotating mandrel draws wire from a wire supply and the wire is laid in place using deflecting rods. After the coil is wound it is held in place in the lath-like machine and compressed by a hydraulic press and then heated by passing current through the wire. The heat softens or melts the wire coating, for example, a suitable epoxy, so that the wires are adhered together in the desired final coil shape. The coil is then removed from the lath-like machine and cooled. In some systems the pressure step is performed prior to heating of the coil. That type of process, using lath-like winding machines, is relatively slow and costly. The mandrel may be relatively massive, for example, 6 inches by 6 inches, and may have to be turned at slow speed, for example, 150 rpm, so that it may take two minutes to wind, compress and heat each coil.
British patent specification No. 1,499,834, published Feb. 1, 1978, to Plessey Company, describes a coil-winding machine for winding saddle-shaped coils. It discusses the previously known types of machines in which a rotatable mandrel of large mass is rotated and draws wire, the wire being laid down by deflecting bars. It states that such machines are relatively large and complex and the deflecting bars are easily deformed. The Plessey specification describes a machine in which a stationary mandrel is wound using two crank arms (flyers) which are rotated and each having a pulley to guide a wire. Each arm is fixed to a hollow shaft which is reciprocated (turning back and forth) about its axis 180.degree. and which serves as a guide for a wire. After the mandrel is wound it is pressed in a pneumatically operated press and heated by internal coils or by passing current through the wire.
In German Offenlegungsschrift No. 2,508,988 of Feb. 5, 1976 to N. V. Philips a coil winding machine for saddle-shaped coils uses two flyer arms in its FIG. 4, each of which is rotated by a driven gear wheel, the description speaking of the arms rotating in opposite directions.
The British patent specification No. 1,497,696, published Jan. 12, 1978, to Philips Electronic And Associated Industries, and its corresponding German Offenlegungsschrift No. 2,552,882, describe apparatus for winding a special type of saddle-shaped coil having series connected sections separated by spaces. The mandrel uses movable pins to form the spaces, the pins being connected to a double-acting piston. At its FIG. 1 a rotary carriage carries a mandrel to a number of positions (work stations) at one of which a single winding arm winds wire onto the mandrel.
In British patent specification No. 1,292,207 published Oct. 11, 1972, to RCA, a saddle-shaped coil is wound in an arbor formed by male and female members having rods or vanes to deflect the wire. In order to improve the accuracy of laying the coil, the arbor has magnets which cooperate with the pulsing of the wire to provide a set of electromagnetic fields for placing the wire.